Search PubMed⌕ Search

Biomedical subjects

E Nakamura

Publications and source records attributed to E Nakamura.

At least 145 records · Page 8Linked to original sources
PubMed1989

Biological age versus physical fitness age.

A population of healthy middle-aged (n = 69) and elderly men (n = 12), who participated in a health promotion program, was studied to determine whether really physically fit individuals are in good biological condition, and also whether improvement of physical fitness in the middle-aged and the elderly reduces their "rate of aging". Biological and physical fitness ages of the individuals studied were estimated from the data for 18 physiological function tests and 5 physical fitness tests, respectively, by a principal component model. The correlation coefficient between the estimated biological and physical fitness ages was 0.72 (p less than 0.01). Detailed analyses of the relationship between the estimated biological and physical fitness ages revealed that those who manifested a higher ("older") physical fitness age did not necessarily have a higher biological age, but those who manifested a lower ("younger") physical fitness age were also found to have a lower biological age. These results suggested that there were considerable individual variations in the relationship between biological condition and physical fitness among individuals with an old physical fitness age, but those who were in a state of high physical fitness maintained a relatively good biological condition. The data regarding the elderly men who had maintained a regular exercise program indicated that their estimated biological ages were considerably younger than the expected values. This might suggest that in older individuals regular physical activity may provide physiological improvements which in turn might reduce "the rate of aging".

Adult↗
PubMed1989

[Remission of a non-haemophilic patient with acquired factor VIII inhibitor treated with infusion of factor VIII and corticosteroid].

A 61-years old woman who had been healthy without history of abnormal bleeding, developed widely spread ecchymosis and intramuscular bleeding in March, 1987. She was hospitalized for this hemorrhagic diathesis in May, 1987 and the following laboratory data were revealed: activated partial thromboplastin time (APTT), 76.7 seconds; factor VIII procoagulant activity, 2%; factor VIII inhibitor, 27 Bethesda units/ml. The inhibitor was an immunoglobulin of IgG type. Her clinical data of the blood were normal, and tests for antibodies, such as RA test, LE test and thyroid test were negative. Physical examination revealed ecchymosis over her right arm and swelling and pain in the right arm. She was first treated with a large dose of factor VIII concentrates, but the effect was insufficient. Then prednisolone was given, which resulted in decreasing of the inhibitor and improvement of the coagulation profiles. This treatment appeared to offer effective control on severe hemorrhage in patients with factor VIII inhibitors.

Autoantibodies↗
PubMed1988

Insulin resistance by unprocessed insulin proreceptors point mutation at the cleavage site.

Failure to cleave the interconnecting site between alpha- and beta-subunit produced insulin proreceptors in the plasma membranes which had markedly low affinity to insulin, leading to extreme insulin resistance in a patient. We performed cDNA sequence analysis of the cleavage site of the insulin proreceptor from the patient. Polymerase chain reaction was used to obtain large amount of cDNA coding for the region including the interconnecting site. A thermostable DNA polymerase, Taq polymerase, successfully produced enough amount of cDNA of the region to be sequenced. The results showed AGG (Arg) to AGT (Ser) point mutation, resulting in the change of interconnecting sequence of the two subunits from -Arg-Lys-Arg-Arg- to -Arg-Lys-Arg-Ser-. These results suggest that the tertial structure change of the cleavage site leads to production of unprocessed insulin proreceptors.

Base Sequence↗
PubMed1988

Metabolic expression of intrinsic developmental programs for dentine and enamel biomineralization in serumless, chemically-defined, organotypic culture.

Biomineralization was investigated using embryonic mouse mandibular first molars (M1) cultured in the presence or absence of fetal calf serum. Metabolic features including cell division and Ca2+ and phosphate incorporation into dentine and enamel extracellular matrices were analyzed. The relative timing and magnitude of DNA synthesis for serumless cultures was comparable to in vivo controls. Isotopic calcium and phosphate incorporation into the mineral phase of dentine and enamel matrices, in the absence of serum, fluctuated during development. Molar tooth morphogenesis, cytodifferentiation, and extracellular matrix formation approximated late crown-stage development in serumless cultures. Von Kossa histochemical staining indicated calcium phosphate salt formation in serumless cultures. Analysis of anhydrous fixation-prepared enamel and dentine representing serumless cultured explants indicated that crystal size and orientation were comparable to in vivo enamel and dentine. In contrast, serum-supplemented cultures showed atypical crystal size and orientation. Calcium/phosphorous (Ca/P) ratio values for serumless cultures after 21 days showed Ca/P enamel values of 2.03 (SD +/- 0.04, p less than 0.025) and dentine values of 1.89 (SD +/- 0.01, p less than 0.025). Electron diffraction patterns of enamel and dentine formed in serumless cultures were principally those of highly-ordered crystalline hydroxyapatite. Our results suggest that tissue-specific dentine and enamel biomineralization is regulated by endogenous factors intrinsic to the developmental program of embryonic tooth organs during serumless culture.

Animals↗
PubMed1988

Assessment of biological age by principal component analysis.

A method of assessing biological age by the application of principal component analysis is reported. Healthy individuals (462) randomly selected from about 6000 men who had taken a 2-day health examination were studied. Out of the 30 physiological variables examined in routine check-ups, 11 variables were selected as suitable for the assessment of biological age based on the results of factor analysis and the physiological meaning of each test. This variable set was then submitted to principal component analysis, and the 1st principal component obtained from this analysis was used as an equation for assessing one's biological age. However, the biological age calculated from this equation is expressed as a score, so the estimated score was transformed to years (biological age) using the T-score idea. The biological age estimated by this method is practically useful and theoretically valid in contrast with the multiple regression model, because this approach eliminates and overcomes the following 2 big problems of the multiple regression model: (1) the distortion of the individual biological age at the regression edges; and (2) a theoretical contradiction in that a perfect model will merely be predicting the subject's chronological age, not his biological age.

Adult↗
PubMed1987

Gas exchange parameters, muscle blood flow and electromechanical properties of the plantar flexors.

Sixteen men were tested to determine VO2max (ml X kg-1 X min-1), anaerobic threshold VO2 (ATVO2) and oxygen kinetics (time constant, T.C.) during running on a treadmill. For measuring maximal calf blood flow (maxBF, ml X 100 ml-1 X min-1), venous occlusion plethysmography was employed immediately following a combination of arterial occlusion and toe raising exercise to exhaustion. In addition, supramaximal electrical stimulations were given to determine maximal calf twitch force (Fmax, N), maximal rate of twitch force development (dF/dt) and relaxation (R X dF/dt, N X ms-1) and electro-mechanical delay time (EMD, ms). Results demonstrated that VO2max, ATVO2 and maxBF were all inversely related to T.C. (p less than 0.05). MaxBF and ATVO2 showed the highest correlation (r = 0.89, p less than 0.01). Stepwise multiple linear regression analyses revealed that variance in VO2max (60%) and ATVO2 (84%) could be accounted for by the combined effects of the following peripheral factors: VO2max = 51,25-3.24(dF/dt) + 0.14(maxBF), and ATVO2 = 11.68 + 0.42(maxBF) - 0.2(Fmax). These findings, together with the results of cluster analysis, suggest a tight link between ATVO2 and peripheral blood flow capacity. On the other hand, a moderate correlation (r = 0.64, p less than 0.01) between VO2max and maxBF might be due in part to individual differences in oxygen extraction-utilization capacity during heavy exercise above anaerobic threshold.

Adult↗
PubMed1987

Arterial pulse wave velocity, Fourier pulsatility index, and blood lipid profiles.

Increased arterial pulse wave velocity (PWV) and decreased Doppler-shifted Fourier pulsatility index (PI) have been utilized clinically to diagnose the presence and severity of peripheral vascular disease. We have examined the relationships between these two diagnostic indices and several lipoprotein atherogenic risk factors, e.g., serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C), and low-density lipo-protein-cholesterol (LDL-C) among 74 healthy male volunteers, aged 20 to 56 yr. The Doppler signal from the radial artery was digitized and processed with the Hamming window and 512-point fast Fourier transform to obtain frequency power spectra and PI index by a desktop computer. PWV was determined on the computer by dividing the distance between two pressure transducers placed over the radial and carotid arteries by the transit time difference between the maximal first derivatives (dP/dt) of the recorded arterial pulse waves. The results indicated that PI was inversely related to TC, LDL-C, and TG (r = -0.50, -0.41, -0.54, respectively, P less than 0.001), but evidenced a positive relationship with the HDL-C/TC ratio (r = 0.69, P less than 0.001). PWV was also significantly correlated to TC (r = 0.40) and TG (r = 0.42), but was inversely associated with the HDL-C/TC ratio (r = -0.45, P less than 0.001). These findings are consistent with the current theory relating lipids to the pathology of atherosclerosis.

Adult↗
PubMed1987

Ultrastructural analysis of enamel formation during in vitro development using chemically-defined medium.

To test the hypothesis that enamel biomineralization is regulated by sequential expression of an intrinsic genetic program, we designed experiments to determine if a serumless, chemically-defined medium is permissive for position-dependent ameloblast differentiation and subsequent enamel tissue-specific biomineralization in vitro. In the absence of serum or other exogenous growth factors, Swiss Webster strain mouse embryonic (15- and 16-days gestation) mandibular first molar tooth organs (cap stage) developed within 21 days in vitro into well-defined molar tooth organs expressing dentine and enamel biomineralization. Analysis of data obtained from von Kossa histochemistry for calcium salt formation, as well as ultrastructural information obtained from x-ray microanalysis, electron diffraction, transmission electron microscopy and scanning electron microscopy documented tissue-specific patterns of calcium hydroxyapatite formation in the absence of serum within organotypic cultures in vitro. An as yet unknown intrinsic genetic program regulates enamel formation in vitro.

Animals↗
PubMed1986

Dog and rat pancreatic phospholipases A2: complete amino acid sequences deduced from complementary DNAs.

We performed molecular cloning of the cDNAs that encode dog and rat pancreatic phospholipases A2 to predict the primary structures of these enzymes. The deduced amino acid sequences exhibited a highly conservative feature which is common to a group of pancreatic phospholipases A2 from various animal species. Furthermore, the structures of the signal sequences of dog and rat pancreatic phospholipases A2 were predicted, although the assignment of the positions cleaved post-translationally is only tentative at the present time.

Amino Acid Sequence↗